Spring coil assemblies are well known for use in mattresses, furniture, cushions and the like. In the case of mattresses, it is known, to use two types of coils in constructing the spring coil assembly. The industry commonly designates these two types of coils as right-hand coils and left-hand coils based on the location and orientation of the end wind of the coil. As used herein and in the appended claims, the terms “right-hand coils” and “left-hand coils” are used only by way of example, and different terminology could be substituted.
FIG. 1 shows a typical prior art coil assembly 10. The prior art coil assembly includes a plurality of substantially identical adjacent rows R1, R2, R3 . . . Each row R consists of alternating right-hand (designated both in FIG. 1 and in the other drawings as RH) and left-hand (designated as LH) coils. The plurality of adjacent rows forms a plurality of adjacent columns C1, C2, C3 . . . Each column C consists entirely of all right-hand coils or all left-hand coils. To remain competitive, manufacturers mass produce the spring coil assemblies, and are therefore limited to coil configurations obtainable with automated assembly machines. Consequently, known spring coil assemblies comprised of left-hand and right-hand coils have been configured substantially as shown in FIG. 1.
To vary the overall firmness of the assembly, it is known to utilize coils made from different gauges of wire, thereby varying the spring characteristics and making the coil assembly softer or firmer. Again, due to the limitations of mass production, all of the right-hand coils are made from the same gauge of wire and all of the left-hand coils are made from the same gauge of wire. While the gauge of wire used for the left-hand coils may be different from the gauge of wire used for the right-hand coils, there are at most only two gauges of wire used in any one spring coil assembly. Since the configuration of coils maintains substantially the same pattern seen in FIG. 1, varying the wire gauge only allows for substantially homogenous variation of the firmness over the entire assembly.
In order to vary the firmness in different areas of the assembly, it is necessary to vary the spacing between the coils in each row. Due to the automated equipment used for mass production, this varied spacing is consistent throughout the rows of the spring coil assembly. This means that softer areas and firmer areas will run across the entire spring assembly in bands, i.e., along columns of coils.